The Thalassocracy of Medain is a kingdom in northern Chandrar. They also style themselves as a Kingdom of Adventurers.
Medain is a nation that - as its name suggests - relies heavily on their navy. So far, there has been no mention how their relationship is with Savere which can be described as a piratocracy.
Aside from that, there are three vast dungeons that are in their borders. All three have been explored for centuries, but they are magical dungeons and still spit out enough threats to employ any number of adventurers. Thus, Medain is also a nation of adventurers and mercenaries.
Medain is currently controlling two other realms, probably as vassals. These have not been mentioned yet.